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use std::collections::HashSet;
use winit::keyboard::KeyCode;
use crate::math::Matrix4;
use crate::constants::camera;
use crate::window::FrameContext;
/// A perspective camera that defines the observer's position and orientation
/// in world space, and supplies the view-projection matrix used by the
/// rendering pipeline.
///
/// # Coordinate system
/// Vertra uses a **Y-up, left-handed** system. The camera looks along the
/// positive Z axis by default.
///
/// # Builder pattern
/// Construct with [`Camera::new`] and then chain the `with_*` setters:
///
/// ```rust,ignore
/// let cam = Camera::new()
/// .with_position([0.0, 5.0, -10.0])
/// .with_fov(60.0)
/// .with_rotation(90.0, -20.0);
/// ```
#[derive(Debug, Copy, Clone, PartialEq)]
pub struct Camera {
/// World-space position of the camera (the "eye" point).
pub eye: [f32; 3],
/// World-space point the camera is looking at.
pub target: [f32; 3],
/// The world-up vector - almost always `[0.0, 1.0, 0.0]`.
pub up: [f32; 3],
/// Viewport aspect ratio (`width / height`). Updated automatically on
/// window resize.
pub aspect: f32,
/// Vertical field of view in **degrees**.
pub fov: f32,
/// Distance to the near clipping plane. Objects closer than this are not
/// rendered.
pub znear: f32,
/// Distance to the far clipping plane. Objects farther than this are not
/// rendered.
pub zfar: f32,
/// Horizontal (yaw) angle in degrees. Drives the `target` direction via
/// [`Camera::update_position`] / [`Camera::rotate`].
pub lr_rot: f32,
/// Vertical (pitch) angle in degrees, clamped to `(-89°, 89°)` to prevent
/// gimbal flip.
pub ud_rot: f32,
}
impl Camera {
/// Create a camera with sensible defaults (eye at `[0, 2, 5]`, looking at
/// the origin, 45° FOV, 0.1–1000 clip range).
pub fn new() -> Self {
Self {
eye: camera::DEFAULT_EYE,
target: camera::DEFAULT_TARGET,
up: camera::UP,
aspect: camera::DEFAULT_ASPECT_RATIO,
fov: camera::DEFAULT_FOV,
znear: camera::NEAR_PLANE,
zfar: camera::FAR_PLANE,
lr_rot: camera::DEFAULT_ROTATION,
ud_rot: camera::DEFAULT_ROTATION,
}
}
/// Override the aspect ratio (`width / height`).
///
/// Called automatically by [`crate::window::Window`] when the viewport is
/// resized, but you can also set it during initial setup.
pub fn with_aspect(mut self, aspect: f32) -> Self {
self.aspect = aspect;
self
}
/// Set the vertical field of view in **degrees**.
pub fn with_fov(mut self, fov: f32) -> Self {
self.fov = fov;
self
}
/// Set the near and far clipping planes.
///
/// * `znear` - objects closer than this distance are clipped.
/// * `zfar` - objects farther than this distance are clipped.
pub fn with_clip_planes(mut self, znear: f32, zfar: f32) -> Self {
self.znear = znear;
self.zfar = zfar;
self
}
/// Set the world-space eye position.
pub fn with_position(mut self, pos: [f32; 3]) -> Self {
self.eye = pos;
self
}
/// Set the yaw (`rotx`) and pitch (`roty`) angles in degrees and
/// recompute [`Camera::target`] accordingly.
pub fn with_rotation(mut self, rotx: f32, roty: f32) -> Self {
self.lr_rot = rotx;
self.ud_rot = roty;
self.update_target_from_angles();
self
}
/// Teleport the camera eye to `new_pos` without changing the look
/// direction.
pub fn update_position(&mut self, new_pos: [f32; 3]) {
self.eye = new_pos;
}
/// Compute the combined view-projection matrix for the current camera
/// state and return it as a [`Matrix4`].
///
/// Used by the pipeline each frame to transform world-space vertices into
/// NDC clip space.
pub fn build_view_projection_matrix(&self) -> Matrix4 {
let view = Matrix4::look_at(self.eye, self.target, self.up);
let proj = Matrix4::perspective(self.fov, self.aspect, self.znear, self.zfar);
proj * view
}
fn update_target_from_angles(&mut self) {
let lr_rad = self.lr_rot.to_radians();
let ud_rad = self.ud_rot.to_radians();
// Calculate a direction vector from angles
let f_x = lr_rad.cos() * ud_rad.cos();
let f_y = ud_rad.sin();
let f_z = lr_rad.sin() * ud_rad.cos();
// The target is just the eye position + the direction vector
self.target = [
self.eye[0] + f_x,
self.eye[1] + f_y,
self.eye[2] + f_z,
];
}
/// Apply a mouse-delta rotation.
///
/// * `dx` - horizontal delta (positive = right in non-inverted mode).
/// * `dy` - vertical delta (positive = down in non-inverted mode).
/// * `inverted` - when `true`, both axes are reversed.
///
/// Pitch is clamped to `±89°` to prevent the camera from flipping.
pub fn rotate(&mut self, dx: f32, dy: f32, inverted: bool) {
if !inverted {
// Moving mouse up, looks up and right, looks right
self.lr_rot -= dx;
self.ud_rot -= dy;
} else {
self.lr_rot += dx;
self.ud_rot += dy;
}
// Constrain pitch so you can't flip the camera upside down
self.ud_rot = self.ud_rot.clamp(-89.0, 89.0);
self.update_target_from_angles();
}
/// Return the normalised **forward** and **right** vectors for the current
/// camera orientation.
///
/// Useful for computing movement directions in response to WASD input.
///
/// # Returns
/// `(forward, right)` - both unit-length, perpendicular to each other and
/// to [`Camera::up`].
pub fn get_directions(&self) -> ([f32; 3], [f32; 3]) {
// Calculate Forward vector (Target - Eye)
let f = [
self.target[0] - self.eye[0],
self.target[1] - self.eye[1],
self.target[2] - self.eye[2],
];
// Normalize Forward
let f_len = (f[0]*f[0] + f[1]*f[1] + f[2]*f[2]).sqrt();
let forward = [f[0] / f_len, f[1] / f_len, f[2] / f_len];
// Calculate Right vector using Cross Product: Forward x Up
// Cross Product Formula:
let r = [
forward[2] * self.up[1] - forward[1] * self.up[2],
forward[0] * self.up[2] - forward[2] * self.up[0],
forward[1] * self.up[0] - forward[0] * self.up[1],
];
let r_len_sq = r[0]*r[0] + r[1]*r[1] + r[2]*r[2];
// Normalize Right
let right = if r_len_sq < 0.0001 {
[1.0, 0.0, 0.0]
} else {
let r_len = r_len_sq.sqrt();
[r[0] / r_len, r[1] / r_len, r[2] / r_len]
};
(forward, right)
}
/// Translate the camera (eye **and** target) by `direction * amount`.
///
/// Moving both points together preserves the look direction.
pub fn move_by(&mut self, direction: [f32; 3], amount: f32) {
let dx = direction[0] * amount;
let dy = direction[1] * amount;
let dz = direction[2] * amount;
// Move the camera position
self.eye[0] += dx;
self.eye[1] += dy;
self.eye[2] += dz;
// Move the focal point so the camera doesn't "pivot"
self.target[0] += dx;
self.target[1] += dy;
self.target[2] += dz;
}
/// Process WASD keyboard movement for the current frame.
///
/// Reads `W/A/S/D` from `keys` and moves the camera along the forward /
/// right axes scaled by `speed * ctx.dt`.
pub fn handle_default_input(&mut self, keys: &HashSet<KeyCode>, speed: f32, ctx: &mut FrameContext) {
let (f, r) = self.get_directions();
let mut move_dir = [0.0, 0.0, 0.0];
if keys.contains(&KeyCode::KeyW) {
move_dir[0] += f[0]; move_dir[1] += f[1]; move_dir[2] += f[2];
}
if keys.contains(&KeyCode::KeyS) {
move_dir[0] -= f[0]; move_dir[1] -= f[1]; move_dir[2] -= f[2];
}
if keys.contains(&KeyCode::KeyD) {
move_dir[0] += r[0]; move_dir[1] += r[1]; move_dir[2] += r[2];
}
if keys.contains(&KeyCode::KeyA) {
move_dir[0] -= r[0]; move_dir[1] -= r[1]; move_dir[2] -= r[2];
}
self.move_by(move_dir, speed * ctx.dt);
}
}